We are studying the molecular biochemistry of gene specific DNA repair and DNA repair coupling with transcription with a view to clarify which gene products are involved and how these processes are regulated as compared to the DNA repair processes in the general, overall bulk of the genome. There are distinct differences in the efficiency of gene- and strand specific DNA repair dependent upon the type of DNA damage, and it is possible that the local degree of chromosomal distortion is the important element in determining the repair response chosen by the cell. We are suggesting that proficient DNA repair is necessary to secure genomic stability, and we find that certain regions of the genome that undergo translocation or rearrangements in the tumor cells are poorly repaired in cells that are susceptible to cancer.